The Gondwana Margin: Proterozoic to Mesozoic
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Hikurangi Plateau: Crustal Structure, Rifted Formation, and Gondwana Subduction History
Article Geochemistry 3 Volume 9, Number 7 Geophysics 3 July 2008 Q07004, doi:10.1029/2007GC001855 GeosystemsG G ISSN: 1525-2027 AN ELECTRONIC JOURNAL OF THE EARTH SCIENCES Published by AGU and the Geochemical Society Click Here for Full Article Hikurangi Plateau: Crustal structure, rifted formation, and Gondwana subduction history Bryan Davy Institute of Geological and Nuclear Sciences, P.O. Box 30368, Lower Hutt, New Zealand ([email protected]) Kaj Hoernle IFM-GEOMAR, Wischhofstraße 1-3, D-24148 Kiel, Germany Reinhard Werner Tethys Geoconsulting GmbH, Wischhofstraße 1-3, D-24148 Kiel, Germany [1] Seismic reflection profiles across the Hikurangi Plateau Large Igneous Province and adjacent margins reveal the faulted volcanic basement and overlying Mesozoic-Cenozoic sedimentary units as well as the structure of the paleoconvergent Gondwana margin at the southern plateau limit. The Hikurangi Plateau crust can be traced 50–100 km southward beneath the Chatham Rise where subduction cessation timing and geometry are interpreted to be variable along the margin. A model fit of the Hikurangi Plateau back against the Manihiki Plateau aligns the Manihiki Scarp with the eastern margin of the Rekohu Embayment. Extensional and rotated block faults which formed during the breakup of the combined Manihiki- Hikurangi plateau are interpreted in seismic sections of the Hikurangi Plateau basement. Guyots and ridge- like seamounts which are widely scattered across the Hikurangi Plateau are interpreted to have formed at 99–89 Ma immediately following Hikurangi Plateau jamming of the Gondwana convergent margin at 100 Ma. Volcanism from this period cannot be separately resolved in the seismic reflection data from basement volcanism; hence seamount formation during Manihiki-Hikurangi Plateau emplacement and breakup (125–120 Ma) cannot be ruled out. -
Redalyc.Sr, C and O Isotope Composition of Marbles from The
Geologica Acta: an international earth science journal ISSN: 1695-6133 [email protected] Universitat de Barcelona España Murra, J.A.; Baldo, E.G.; Galindo, C.; Casquet, C.; Pankhurst, R.J.; Rapela, C.W.; Dahlquist, J. Sr, C and O isotope composition of marbles from the Sierra de Ancasti, Eastern Sierras Pampeanas, Argentina: age and constraints for the Neoproterozoic-Lower Paleozoic evolution of the proto- Gondwana margin Geologica Acta: an international earth science journal, vol. 9, núm. 1, marzo, 2011, pp. 79-92 Universitat de Barcelona Barcelona, España Available in: http://www.redalyc.org/articulo.oa?id=50522124008 How to cite Complete issue Scientific Information System More information about this article Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Journal's homepage in redalyc.org Non-profit academic project, developed under the open access initiative Geologica Acta, Vol.9, Nº 1, March 2011, 79-92 DOI: 10.1344/105.000001645 Available online at www.geologica-acta.com Sr, C and O isotope composition of marbles from the Sierra de Ancasti, Eastern Sierras Pampeanas, Argentina: age and constraints for the Neoproterozoic–Lower Paleozoic evolution of the proto-Gondwana margin 1 1 2 2 3 4 1 J.A. MURRA E.G. BALDO C. GALINDO C. CASQUET R.J. PANKHURST C.W. RAPELA J. DAHLQUIST 1 CICTERRA (Universidad Nacional de Córdoba - Conicet) Av. Vélez Sarsfield 1611, 5016 Córdoba, Argentina. Murra E-mail: [email protected] Baldo E-mail: [email protected] Dahlquist E-mail: [email protected] 2 Departamento. Petrología y Geoquímica Facultad de Ciencias Geológicas, Inst. -
Vulnerable Marine Ecosystems – Processes and Practices in the High Seas Vulnerable Marine Ecosystems Processes and Practices in the High Seas
ISSN 2070-7010 FAO 595 FISHERIES AND AQUACULTURE TECHNICAL PAPER 595 Vulnerable marine ecosystems – Processes and practices in the high seas Vulnerable marine ecosystems Processes and practices in the high seas This publication, Vulnerable Marine Ecosystems: processes and practices in the high seas, provides regional fisheries management bodies, States, and other interested parties with a summary of existing regional measures to protect vulnerable marine ecosystems from significant adverse impacts caused by deep-sea fisheries using bottom contact gears in the high seas. This publication compiles and summarizes information on the processes and practices of the regional fishery management bodies, with mandates to manage deep-sea fisheries in the high seas, to protect vulnerable marine ecosystems. ISBN 978-92-5-109340-5 ISSN 2070-7010 FAO 9 789251 093405 I5952E/2/03.17 Cover photo credits: Photo descriptions clockwise from top-left: Acanthagorgia spp., Paragorgia arborea, Vase sponges (images courtesy of Fisheries and Oceans, Canada); and Callogorgia spp. (image courtesy of Kirsty Kemp, the Zoological Society of London). FAO FISHERIES AND Vulnerable marine ecosystems AQUACULTURE TECHNICAL Processes and practices in the high seas PAPER 595 Edited by Anthony Thompson FAO Consultant Rome, Italy Jessica Sanders Fisheries Officer FAO Fisheries and Aquaculture Department Rome, Italy Merete Tandstad Fisheries Resources Officer FAO Fisheries and Aquaculture Department Rome, Italy Fabio Carocci Fishery Information Assistant FAO Fisheries and Aquaculture Department Rome, Italy and Jessica Fuller FAO Consultant Rome, Italy FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS Rome, 2016 The designations employed and the presentation of material in this information product do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations (FAO) concerning the legal or development status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. -
Campbell Plateau: a Major Control on the SW Pacific Sector of The
Ocean Sci. Discuss., doi:10.5194/os-2017-36, 2017 Manuscript under review for journal Ocean Sci. Discussion started: 15 May 2017 c Author(s) 2017. CC-BY 3.0 License. Campbell Plateau: A major control on the SW Pacific sector of the Southern Ocean circulation. Aitana Forcén-Vázquez1,2, Michael J. M. Williams1, Melissa Bowen3, Lionel Carter2, and Helen Bostock1 1NIWA 2Victoria University of Wellington 3The University of Auckland Correspondence to: Aitana ([email protected]) Abstract. New Zealand’s subantarctic region is a dynamic oceanographic zone with the Subtropical Front (STF) to the north and the Subantarctic Front (SAF) to the south. Both the fronts and their associated currents are strongly influenced by topog- raphy: the South Island of New Zealand and the Chatham Rise for the STF, and Macquarie Ridge and Campbell Plateau for the SAF. Here for the first time we present a consistent picture across the subantarctic region of the relationships between front 5 positions, bathymetry and water mass structure using eight high resolution oceanographic sections that span the region. Our results show that the northwest side of Campbell Plateau is comparatively warm due to a southward extension of the STF over the plateau. The SAF is steered south and east by Macquarie Ridge and Campbell Plateau, with waters originating in the SAF also found north of the plateau in the Bounty Trough. Subantarctic Mode Water (SAMW) formation is confirmed to exist south of the plateau on the northern side of the SAF in winter, while on Campbell Plateau a deep reservoir persists into the following 10 autumn. -
A New Record Ofrodinia Break-Up in the Western Sierras Pampeanas of Argentina
A-type magmatism in the sierras ofMaz and Espinal: A new record ofRodinia break-up in the Western Sierras Pampeanas of Argentina Fernando CoIomboa,,,, Edgardo G.A. BaIdoa, Cesar Casquetb, RobertJ. PankhurstC, Carmen Galindob, CarIos W. RapeIa d, Juan A. DahIquista, C. Mark Fanninge a Departamento de Geologfa - FCEFyN, Universidad NacionaI de Cordoba, Wlez Sarsfield 1611, X5016GCA Cordoba, Argentina b Departamento de Petrologfa y Geoquimica, Universidad Complutense, 28040 Madrid, Spain C British Geological Survey, Keyworth, Nottingham NG12 5GG, England, United Kingdom d Centro de Investigaciones Geologicas, Universidad Nacional de La Plata, 1900 La Plata, Argentina e Research School of Earth Sciences, The Australian National University, Canberra, Australia A BST RAC T Two orthogneisses have been recognized in the sierras of Espinal and Maz (Wes tern Sierras Pampeanas, NWArgentina) that were emplaced within a Grenvillian metasedimentary sequence. Microcline, plagio clase and quartz are the main rock-forming minerals, with accessory zircon, apatite-(CaF), magnetite, biotite (Fe/(Fe + Mg) = 0.88-0.91). ferropargasite (Fetotal/(Fetotal + Mg) = 0.88-0.89), titanite (with up to 3 1.61 wt% Y203) and an REE-rich epidote. REE-poor epidote and zoned garnet (Ca and Fe + -rich) are meta Keywords: morphic minerals, while muscovite, carbonates and chlorite are secondary phases. Texture is mylonitic. Rodinia Two representative samples are classified as granite (from Sierra de Espinal) and granodiorite/tonalite U-Pb SHRIMP dating Anorogenic magmatism (from Sierra de Maz) on the grounds of immobile trace elements. Some trace element contents are rather Mesoproterozoic high (Zr: 603 and 891 ppm, Y: 44 and 76 ppm, 10,000 x Ga/AI: 2.39-3.89) and indicate an affiliation with Western Sierras Pampeanas A-type granites (more specifically, the A2 group). -
Early Evolution of the Proto-Andean Margin of South America
Early evolution of the Proto-Andean margin of South America C. W. Rapela Centro de Investigaciones Geológicas, Universidad Nacional de La Plata, Calle 1 No. 644, 1900 La Plata, Argentina R. J. Pankhurst British Antarctic Survey, Cambridge CB30ET, United Kingdom C. Casquet Departamento de Petrología y Geoquímica, Universidad Complutense, 28040 Madrid, Spain E. Baldo J. Saavedra CSIC, Instituto de Agrobiología y Recursos Naturales, 37071 Salamanca, Spain C. Galindo Departamento de Petrología y Geoquímica, Universidad Complutense, 28040 Madrid, Spain ABSTRACT INTRODUCTION From a detailed study of a 500 km transect in the Sierras Pampeanas, central-west Argen- The evolution of the Gondwana margin pro- tina, two pre-Silurian tectono-magmatic episodes are recognized and defined, each culminating posed here is based on new geochemical, isotopic, in micro-continental collisions against the proto-Andean margin of Gondwana. The Pampean petrological, and sedimentological data from a orogeny started in Early Cambrian time with short-lived subduction, indicated by ca. 535 Ma 500 km traverse across the Eastern Sierras Pam- calc-alkaline granitoids. Following Pampean terrane collision, burial to granulite facies condi- peanas and Precordillera (Fig. 1). Pre-Silurian tions (ca. 9 kbar) generated widespread migmatites and ca. 520 Ma highly peraluminous gran- metamorphic and magmatic history is inferred ites in the Eastern Sierras Pampeanas. After brief quiescence, a second major episode, the from (1) dating by conventional U-Pb on abraded Famatinian orogeny, started with subduction ca. 490 Ma, forming a wide continental arc and zircons, U-Pb SHRIMP analyses, and whole-rock ensialic backarc basin. This heralded the approach of Laurentia to Gondwana, during which Rb-Sr and K-Ar, (2) thermo-barometry based on the Precordillera terrane separated from the southern Appalachian region, finally colliding with microprobe mineral analyses, and (3) Nd and Sr Gondwana in Silurian–Devonian time. -
Geology: Ordovician Paleogeography and the Evolution of the Iapetus Ocean
Ordovician paleogeography and the evolution of the Iapetus ocean Conall Mac Niocaill* Department of Geological Sciences, University of Michigan, 2534 C. C. Little Building, Ben A. van der Pluijm Ann Arbor, Michigan 48109-1063. Rob Van der Voo ABSTRACT thermore, we contend that the combined paleomagnetic and faunal data ar- Paleomagnetic data from northern Appalachian terranes identify gue against a shared Taconic history between North and South America. several arcs within the Iapetus ocean in the Early to Middle Ordovi- cian, including a peri-Laurentian arc at ~10°–20°S, a peri-Avalonian PALEOMAGNETIC DATA FROM IAPETAN TERRANES arc at ~50°–60°S, and an intra-oceanic arc (called the Exploits arc) at Displaced terranes occur along the extent of the Appalachian-Cale- ~30°S. The peri-Avalonian and Exploits arcs are characterized by Are- donian orogen, although reliable Ordovician paleomagnetic data from Ia- nigian to Llanvirnian Celtic fauna that are distinct from similarly aged petan terranes have only been obtained from the Central Mobile belt of the Toquima–Table Head fauna of the Laurentian margin, and peri- northern Appalachians (Table 1). The Central Mobile belt separates the Lau- Laurentian arc. The Precordillera terrane of Argentina is also charac- rentian and Avalonian margins of Iapetus and preserves remnants of the terized by an increasing proportion of Celtic fauna from Arenig to ocean, including arcs, ocean islands, and ophiolite slivers (e.g., Keppie, Llanvirn time, which implies (1) that it was in reproductive communi- 1989). Paleomagnetic results from Arenigian and Llanvirnian volcanic units cation with the peri-Avalonian and Exploits arcs, and (2) that it must of the Moreton’s Harbour Group and the Lawrence Head Formation in cen- have been separate from Laurentia and the peri-Laurentian arc well tral Newfoundland indicate paleolatitudes of 11°S (Table 1), placing them before it collided with Gondwana. -
Redalyc.Lost Terranes of Zealandia: Possible Development of Late
Andean Geology ISSN: 0718-7092 [email protected] Servicio Nacional de Geología y Minería Chile Adams, Christopher J Lost Terranes of Zealandia: possible development of late Paleozoic and early Mesozoic sedimentary basins at the southwest Pacific margin of Gondwanaland, and their destination as terranes in southern South America Andean Geology, vol. 37, núm. 2, julio, 2010, pp. 442-454 Servicio Nacional de Geología y Minería Santiago, Chile Available in: http://www.redalyc.org/articulo.oa?id=173916371010 How to cite Complete issue Scientific Information System More information about this article Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Journal's homepage in redalyc.org Non-profit academic project, developed under the open access initiative Andean Ge%gy 37 (2): 442-454. July. 2010 Andean Geology formerly Revista Geológica de Chile www.scielo.cl/andgeol.htm Lost Terranes of Zealandia: possible development of late Paleozoic and early Mesozoic sedimentary basins at the southwest Pacific margin of Gondwana land, and their destination as terranes in southern South America Christopher J. Adams GNS Science, Private Bag 1930, Dunedin, New Zealand. [email protected] ABSTRACT. Latesl Precambrian to Ordovician metasedimentary suecessions and Cambrian-Ordovician and Devonian Carboniferous granitoids form tbe major par! oftbe basemenl of soutbem Zealandia and adjacenl sectors ofAntarctica and southeastAustralia. Uplift/cooling ages ofthese rocks, and local Devonian shallow-water caver sequences suggest tbal final consolidation oftbe basemenl occurred tbrough Late Paleozoic time. A necessary consequence oftlris process would have been contemporaneous erosion and tbe substantial developmenl of marine sedimentary basins al tbe Pacific margin of Zealandia. -
Mesh-Based Tectonic Reconstruction: Andean Margin Evolution Since the Cretaceous
Mesh-based tectonic reconstruction: Andean margin evolution since the Cretaceous Tomas P. O'Kane, Gordon S. Lister Journal of the Virtual Explorer, Electronic Edition, ISSN 1441-8142, volume 43, paper 1 In: (Eds.) Stephen Johnston and Gideon Rosenbaum, Oroclines, 2012. Download from: http://virtualexplorer.com.au/article/2011/297/mesh-based-tectonic-reconstruction Click http://virtualexplorer.com.au/subscribe/ to subscribe to the Journal of the Virtual Explorer. Email [email protected] to contact a member of the Virtual Explorer team. Copyright is shared by The Virtual Explorer Pty Ltd with authors of individual contributions. Individual authors may use a single figure and/or a table and/or a brief paragraph or two of text in a subsequent work, provided this work is of a scientific nature, and intended for use in a learned journal, book or other peer reviewed publication. Copies of this article may be made in unlimited numbers for use in a classroom, to further education and science. The Virtual Explorer Pty Ltd is a scientific publisher and intends that appropriate professional standards be met in any of its publications. Journal of the Virtual Explorer, 2012 Volume 43 Paper 1 http://virtualexplorer.com.au/ Mesh-based tectonic reconstruction: Andean margin evolution since the Cretaceous Tomas P. O'Kane Research School of Earth Sciences, The Australian National University, Canberra 0200 Australia. Email: [email protected] Gordon S. Lister Research School of Earth Sciences, The Australian National University, Canberra 0200 Australia. Abstract: In this contribution we demonstrate an example of what can be described as mesh-based tectonic reconstruction. -
Bathymetry of the New Zealand Region
ISSN 2538-1016; 11 NEW ZEALAND DEPARTMENT OF SCIENTIFIC AND INDUSTRIAL RESEARCH BULLETIN 161 BATHYMETRY OF THE NEW ZEALAND REGION by J. W. BRODIE New Zealand Oceanographic Institute Wellington New Zealand Oceanographic Institute Memoir No. 11 1964 This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ Fromispiece: The survey ship HMS Penguin from which many soundings were obtained around the New Zealand coast and in the south-west Pacific in the decade around 1900. (Photograph by courtesy of the Trustees, National Maritime Museum, Greenwich.) This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ NEW ZEALAND DEPARTMENT OF SCIENTIFIC AND INDUSTRIAL RESEARCH BULLETIN 161 BATHYMETRY OF THE NEW ZEALAND REGION by J. W. BRODIE New Zealand Oceanographic Institute Wellington New Zealand Oceanographic Institute Memoir No. 11 1964 Price: 15s. This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ CONTENTS Page No. ABSTRACT 7 INTRODUCTION 7 Sources of Data 7 Compilation of Charts 8 EARLIER BATHYMETRIC INTERPRETATIONS 10 Carte Gen�rale Bathymetrique des Oceans 17 Discussion 19 NAMES OF OCEAN FLOOR FEATURES 22 Synonymy of Existing Names 22 Newly Named Features .. 23 FEATURES ON THE CHARTS 25 Major Morphological Units 25 Offshore Banks and Seamounts 33 STRUCTURAL POSITION OF NEW ZEALAND 35 The New Zealand Plateau 35 Rocks of the New Zealand Plateau 37 Crustal Thickness Beneath the New Zealand Plateau 38 Chatham Province Features 41 The Alpine Fault 41 Minor Irregularities on the Sea Floor 41 SEDIMENTATION IN THE NEW ZEALAND REGION . -
4 Three-Dimensional Density Model of the Nazca Plate and the Andean Continental Margin
76 4 Three-dimensional density model of the Nazca plate and the Andean continental margin Authors: Andrés Tassara, Hans-Jürgen Götze, Sabine Schmidt and Ron Hackney Paper under review (September 27th, 2005) by the Journal of Geophysical Research Abstract We forward modelled the Bouguer anomaly in a region encompassing the Pacific ocean (east of 85°W) and the Andean margin (west of 60°W) between northern Peru (5°S) and Patagonia (45°S). The three-dimensional density structure used to accurately reproduce the gravity field is simple. The oceanic Nazca plate is formed by one crustal body and one mantle lithosphere body overlying a sub-lithospheric mantle, but fracture zones divide the plate into seven along-strike segments. The subducted slab was modelled to a depth of 410 km, has the same structure as the oceanic plate, but it is subdivided into four segments with depth. The continental margin consists of one upper-crustal and one lower-crustal body without lateral subdivision, whereas the mantle has two bodies for the lithosphere and two bodies for the asthenosphere that are separated across-strike by the downward prolongation of the eastern limit of active volcanism. We predefined the density for each body after studying its dependency on composition of crustal and mantle materials and pressure-temperature conditions appropriate for the Andean setting. A database containing independent geophysical information constrains the geometry of the subducted slab, locally the Moho of the oceanic and continental crusts, and indirectly the lithosphere-asthenosphere boundary (LAB) underneath the continental plate. Other geometries, especially that of the intracrustal density discontinuity (ICD) in the continental margin, were not constrained and are the result of fitting the observed and calculated Bouguer anomaly during the forward modelling. -
Crustal-Seismicity.Pdf
Tectonophysics 786 (2020) 228450 Contents lists available at ScienceDirect Tectonophysics journal homepage: www.elsevier.com/locate/tecto Crustal seismicity in the Andean Precordillera of Argentina using seismic broadband data T ⁎ Agostina Venerdinia,b, , Patricia Alvaradoa,b, Jean-Baptiste Ammiratia,1, Marcos Podestaa, Luciana Lópezc, Facundo Fuentesd, Lepolt Linkimere, Susan Beckf a Grupo de Sismotectónica, Centro de Investigaciones de la Geósfera y la Biósfera (Consejo Nacional de Investigaciones Científicas y Técnicas CONICET– Facultad de Ciencias Exactas, Físicas y Naturales, UNSJ), San Juan, Argentina b Departamento de Geofísica y Astronomía, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de San Juan, San Juan, Argentina c Instituto Nacional de Prevención Sísmica, San Juan, Argentina d YPF S.A., Buenos Aires, Argentina e Escuela Centroamericana de Geología, Universidad de Costa Rica, San José, Costa Rica f Department of Geosciences, University of Arizona, Tucson, AZ, United States ARTICLE INFO ABSTRACT Keywords: In this study, we analyze 100 crustal Precordilleran earthquakes recorded in 2008 and 2009 by 52 broadband Crust seismic stations from the SIEMBRA and ESP, two temporary experiments deployed in the Pampean flat slab Focal mechanism region, between the Andean Cordillera and the Sierras Pampeanas in the Argentine Andean backarc region. Fold-thrust belt In order to determine more accurate hypocenters, focal mechanisms and regional stress orientations, we Andean retroarc relocated 100 earthquakes using the JHD technique and a local velocity model. The focal depths of our relocated Flat slab events vary between 6 and 50 km. We estimated local magnitudes between 0.4 ≤ M ≤ 5.3 and moment South America L magnitudes between 1.3 ≤ Mw ≤ 5.3.